For hundreds of years muzzle loaded firearms have relied upon use of an ignition orifice or port positioned adjacent the breech end of the barrel. This orifice or port allowed an ignition spark or flame to be transmitted from a point external of the gun barrel inside the barrel to the primary powder charge. This was followed, in most instances, by the explosion of that powder charge and the simultaneous expulsion of the bullet from the firearm.
It is well known that this process involved the rapid movement of sparks, a type of flame or hot gases. Over time this causes wear of the ignition ports. Further, it is also well known that the size and effective diameter of those ports vary appreciably with continued use and deteriorate over time. This deterioration is primarily due to the formation of a crust about the interior end of the orifice formed from powder residue that accompanies such use, that residue being comprised of the reaction between the charcoal, moisture, sulphur and nitrates from which the powder is comprised.
Various nozzle designs have been used in the past. One such design is shown in FIG. 1. This is a standard coned touchhole liner previously used only in flintlock guns. In flintlock weapons, the hammer included a piece of flint designed to strike a frizzen when the trigger was pulled. Most desirably this would produce one or more sparks adjacent the touchhole. The touchhole liner was made relatively large at its internal diameter so that the spark entering therein would be directed at the powder charge previously positioned in the breech end of the barrel. It was desirable to make the passageway from the flint to the powder charge as close as possible and frequently the exterior end of the touchhold liner would be filed down so that its exterior end lay flush with the exterior of the firearm.
These flintlock touchhole devices were not useful when the ignition system changed to use percussion caps. There was not a reduced portion on which the cap could be positioned and the percussion cap comprised a slightly different approach at ignition which required a different style and length nipple.
Various types of ignition nipples used with percussion caps are shown, for example, in U.S. Patents to Hopkins, U.S. Pat. No. 36,464, Talbott, U.S. Pat. No. 92,398, Vaughn, U.S. Pat. No. 4,114,303, Peterson, U.S. Pat. No. 4,123,867, Ives, U.S. Pat. No. 4,163,335 and Pawlak et al, U.S. Pat. No. 4,186,506.
The nipple shown in Hopkins screws into the breech end of the barrel and appears to include an internal passageway that is comprised of two tapered sections that join directly with one another at a point central along the bore. Talbott begins with a short small diameter cylindrical bore, similar to the touchhole liner, with the bore then flaring outwardly into an elongated, conically shaped section adjacent the base end of the nipple structure. Each of the more recent designs in Vaughn, Peterson, Ives and Pawlak et al show the concept of starting with a relatively large diameter primary chamber which terminates at a very small diameter bore that leads into the breech end of the barrel.
It is common that these nipples all screw into one or more types of mounting blocks, each of which includes an internal passageway that in turn leads to the primary powder charge. These mounting blocks can either be of the bolster type, a drum type or a mule ear (side slapper) type.
One problem associated with ignition nipples available today relates directly to the small size of the bores at the base of such nipples. Peterson attempts to overcome bore wear problems by employing an insert sleeve formed from a material which exhibits improved wear properties due to the use of a heat and wear resistant material. However, the area around the small diameter bore at the base of the nipple inevitably crests over due to powder residue buildup restricting flow through that small bore. This reduces the time the nipple remains useful and limits the effective diameter of that bore which leads to unreliable ignition and poses potential safety hazards.